const logger = require('@overleaf/logger') const Errors = require('./Errors') const RequestParser = require('./RequestParser') const Metrics = require('@overleaf/metrics') // The lock timeout should be higher than the maximum end-to-end compile time. // Here, we use the maximum compile timeout plus 2 minutes. const LOCK_TIMEOUT_MS = RequestParser.MAX_TIMEOUT * 1000 + 120000 const LOCKS = new Map() function acquire(key) { const currentLock = LOCKS.get(key) if (currentLock != null) { if (currentLock.isExpired()) { logger.warn({ key }, 'Compile lock expired') currentLock.release() } else { throw new Errors.AlreadyCompilingError('compile in progress') } } Metrics.gauge('concurrent_compile_requests', LOCKS.size) const lock = new Lock(key) LOCKS.set(key, lock) return lock } class Lock { constructor(key) { this.key = key this.expiresAt = Date.now() + LOCK_TIMEOUT_MS } isExpired() { return Date.now() >= this.expiresAt } release() { const lockWasActive = LOCKS.delete(this.key) if (!lockWasActive) { logger.error({ key: this.key }, 'Lock was released twice') } if (this.isExpired()) { Metrics.inc('compile_lock_expired_before_release') } } } module.exports = { acquire }